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From:   Kees Cook <keescook@chromium.org>
To:     Ido Schimmel <idosch@nvidia.com>
Cc:     Kees Cook <keescook@chromium.org>, Petr Machata <petrm@nvidia.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, linux-kernel@vger.kernel.org,
        linux-hardening@vger.kernel.org, llvm@lists.linux.dev
Subject: [PATCH 2/5] mlxsw: core: Annotate struct mlxsw_env with __counted_by
Date:   Fri, 29 Sep 2023 11:07:41 -0700
Message-Id: <20230929180746.3005922-2-keescook@chromium.org>
In-Reply-To: <20230929180611.work.870-kees@kernel.org>
References: <20230929180611.work.870-kees@kernel.org>
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Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct mlxsw_env.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Ido Schimmel <idosch@nvidia.com>
Cc: Petr Machata <petrm@nvidia.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/net/ethernet/mellanox/mlxsw/core_env.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/core_env.c b/drivers/net/ethernet/mellanox/mlxsw/core_env.c
index d637c0348fa1..a129e0df1d07 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/core_env.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core_env.c
@@ -34,7 +34,7 @@ struct mlxsw_env {
 	u8 num_of_slots; /* Including the main board. */
 	u8 max_eeprom_len; /* Maximum module EEPROM transaction length. */
 	struct mutex line_cards_lock; /* Protects line cards. */
-	struct mlxsw_env_line_card *line_cards[];
+	struct mlxsw_env_line_card *line_cards[] __counted_by(num_of_slots);
 };
 
 static bool __mlxsw_env_linecard_is_active(struct mlxsw_env *mlxsw_env,
-- 
2.34.1